Solid-state imaging device having a voltage clipping circuit to prevent image defects and driving method thereof
View Patent ↗It is an object of the present invention to provide a solid-state imaging device capable of prevent image defects from appearing in an outputted image while suppressing increase in a layout area with a simple circuit structure and is an MOS solid-state imaging device. The MOS solid-state imaging device includes pixels which outputs signals corresponding to intensity of incident light, vertical signal lines which are respectively provided to columns of the pixels and each of which transmits the signals from said pixels in a column direction, and column amplifier circuits that amplify the signals from the pixels and are respectively connected to the vertical signal lines, and each of the column amplifier circuits includes a voltage clipping circuit includes a voltage clipping circuit which limits a maximum output voltage of said column amplifier circuit.
1. A solid-state imaging device comprising:
pixels arranged in a matrix and each of which outputs signals corresponding to intensity of incident light;
vertical signal lines which are respectively provided to columns of the pixels and each of which transmits the signals from said pixels in a column direction; and
column amplifier circuits that amplify the signals from the pixels and column Correlated Double Sampling CDS circuits, which are respectively connected to the vertical signal lines;
wherein each of said column amplifier circuits includes a voltage clipping circuit which limits a maximum output voltage of said column amplifier circuit, and an amplifier transistor whose drain is connected to an output terminal of the column amplifier circuit and whose source is grounded, and
the voltage clipping circuit includes a clipping transistor whose source is connected to the output terminal of the column amplifier circuit, whose drain is connected to a gate of the amplifier transistor, and whose gate is connected to a reference potential.
2. The solid-state imaging device according to claim l,
wherein each of said column amplifier circuits includes a switched capacitor amplifier having:
an input capacitance, one terminal of which is connected to one of said vertical signal lines;
a feedback capacitance arranged between another terminal of said input capacitance and the output terminal of said column amplifier circuit; and
a first current source transistor whose drain is connected to the output terminal of said column amplifier circuit and whose source is connected to a constant potential.
3. The solid-state imaging device according to claim 2 ,
wherein a gate of said first current source transistor is connected to the reference potential to which the gate of said clipping transistor is connected.
4. The solid-state imaging device according to claim 2 ,
wherein a gate width of said first current source transistor is approximately equal to a gate width of said clipping transistor.
5. The solid-state imaging device according to claim 2 ,
wherein a gate length of said first current source transistor is approximately equal to a gate length of said clipping transistor.
6. The solid-state imaging device according to claim 1 ,
wherein each of said column amplifier circuits includes a switched capacitor amplifier having:
an input capacitance whose one terminal is connected to one of said vertical signal lines;
a feedback capacitance arranged between another terminal of said input capacitance and the output terminal of said column amplifier circuit;
a first current source transistor whose drain is connected to the output terminal of said column amplifier circuit; and
a second current source transistor whose drain is connected to a source of said first current source transistor and whose source is connected to a constant potential.
7. The solid-state imaging device according to claim 6 ,
wherein a gate of said first current source transistor is connected to the reference potential to which the gate of said clipping transistor is connected.
8. The solid-state imaging device according to claim 7 ,
wherein a gate width of said first current source transistor is approximately equal to a gate width of said clipping transistor.
9. The solid-state imaging device according to claim 8 ,
wherein a gate length of said first current source transistor is approximately equal to a gate length of said clipping transistor.
10. The solid-state imaging device according to claim 9 ,
wherein each of said column amplifier circuits includes a column Analog Digital Converter (ADC).
11. The solid-state imaging device according to claim 1 ,
wherein each of said column amplifier circuits includes a column Analog Digital Converter (ADC).
12. An imaging apparatus comprising
the solid-state imaging device according to claim 1 .
13. A driving method for a solid-state imaging device comprising:
outputting signals corresponding to intensity of incident light from pixels, selected among pixels arranged in a matrix, to vertical signal lines which are respectively provided to columns of the pixels, and each of which transmits the signals from said pixels in a column direction;
amplifying the signals outputted to the vertical signal lines in column amplifier circuits which are respectively connected to the vertical signal lines, and outputting the amplified signals to a horizontal common signal line;
wherein in said amplifying, the signals are outputted while limiting a maximum output voltage of each of said column amplifier circuits by a voltage clipping circuit provided in each of the column amplifier circuits,
wherein each of said column amplifier circuits includes an amplifier transistor whose drain is connected to an output terminal of the column amplifier circuit and whose source is grounded, and the voltage clipping circuit of the respective column amplifier circuit includes a clipping transistor whose source is connected to the output terminal of the column amplifier circuit, whose drain is connected to a gate of the amplifier transistor, and whose gate is connected to a reference potential.